DIY film dryer

philipus · Jun 11, 2019

Hello everybody

I just wanted to share the prototype of a film dryer I've built. It's straight forward, easy and inexpensive to build. The one thing I would like to add is a thin air filter which doesn't block the airflow too much because I have chosen a pretty weak fan (deliberately). Any ideas on that?

https://philipus.com/project-film-dryer-prototype

Br
Philip

Luckless · Jun 11, 2019

Maybe take a walk through some hardware and automotive stores, and look for a round filter of a rating you're happy with?

Your vent design may also have a big impact on how much dust something like this collects. - I've found it was easy to design cases that accidentally end up kicking up more dust than needed due to how hard and concentrated the exit vent gasses end up being. And if you restrict intake too much, you may end up drawing air in through other holes in the case, bypassing your filtering.

Rick A · Jun 11, 2019

Replacement open cell A/C foam air filter from nearly any hardware store. Use the fan to exhaust air out of, not blow into the dryer, and use the filter on the intake..

RalphLambrecht · Jun 11, 2019

philipus said:
Hello everybody

I just wanted to share the prototype of a film dryer I've built. It's straight forward, easy and inexpensive to build. The one thing I would like to add is a thin air filter which doesn't block the airflow too much because I have chosen a pretty weak fan (deliberately). Any ideas on that?

https://philipus.com/project-film-dryer-prototype

Br
Philip

The trick with air filters is surface area. You can choose a weak fan if the filter has a large surface area for the air to pass through.

philipus · Jun 12, 2019

Thank you for the replies.

Luckless said:
Maybe take a walk through some hardware and automotive stores, and look for a round filter of a rating you're happy with?

Your vent design may also have a big impact on how much dust something like this collects. - I've found it was easy to design cases that accidentally end up kicking up more dust than needed due to how hard and concentrated the exit vent gasses end up being. And if you restrict intake too much, you may end up drawing air in through other holes in the case, bypassing your filtering.

That's a good idea, thank you. Re the vent design, I haven't found that the vent moves dust. But in the new version I will instead use a simple net. I'll publish a new article on that later.

Rick A said:
Replacement open cell A/C foam air filter from nearly any hardware store. Use the fan to exhaust air out of, not blow into the dryer, and use the filter on the intake..

Thank you Rick, I had not thought of such filters. Excellent idea.

Why would it be better to use that airflow as opposed to blowing into the dryer?

RalphLambrecht said:
The trick with air filters is surface area. You can choose a weak fan if the filter has a large surface area for the air to pass through.

Thank you Ralph. I guess that would require a larger intake? Ideally I would like to keep the dryer smallish.

Rick A · Jun 12, 2019

Thank you Rick, I had not thought of such filters. Excellent idea.
Why would it be better to use that airflow as opposed to blowing into the dryer?

I built a drying cabinet years ago, the oldtimer who helped me had me do it that way, his reason was less chance to blow something against the film. I see you have a low powered fan, perfect for this application, you really don't need a jet stream of air on the film, just move the air as it picks up the moisture from the film. My last cabinet had no fan, but plenty of ventilation and worked nearly as good as a fan unit, I do not favor heated dryers, I like the film to dry slower, I believe there's less stress on the emulsion. These days I just hang the film in my darkroom. I have a small electrostatic air cleaner that runs constantly, no dust issues at all.

philipus · Jun 12, 2019

Thank you Rick. That all makes sense to me. Luckily my design is pretty modular so I can easily switch the airflow.

Rick A said:
Thank you Rick, I had not thought of such filters. Excellent idea.
Why would it be better to use that airflow as opposed to blowing into the dryer?

I built a drying cabinet years ago, the oldtimer who helped me had me do it that way, his reason was less chance to blow something against the film. I see you have a low powered fan, perfect for this application, you really don't need a jet stream of air on the film, just move the air as it picks up the moisture from the film. My last cabinet had no fan, but plenty of ventilation and worked nearly as good as a fan unit, I do not favor heated dryers, I like the film to dry slower, I believe there's less stress on the emulsion. These days I just hang the film in my darkroom. I have a small electrostatic air cleaner that runs constantly, no dust issues at all.

mpirie · Jun 12, 2019

What about using a carbon air filter sheet from a cooker hood?

I've seen various densities which shouldn't restrict the air flow, but make sure there's no particulates passing through.

Mike

Rick A · Jun 12, 2019

https://www.amazon.com/Frost-King-C...l+foam+filter&qid=1560338312&s=gateway&sr=8-3

philipus · Jun 13, 2019

Thank you for this suggestion Mike. I had not thought of such filters to be honest.

mpirie said:
What about using a carbon air filter sheet from a cooker hood?

I've seen various densities which shouldn't restrict the air flow, but make sure there's no particulates passing through.

Mike

Thanks Rick, that does look like a workable filter to me.

Rick A said:
https://www.amazon.com/Frost-King-C...l+foam+filter&qid=1560338312&s=gateway&sr=8-3

mpirie · Jun 13, 2019

My Durst UT100 film dryer has a carbon filter above the fan which then drays air down through the filter before the air reaches the film.

Mike

philipus · Jun 13, 2019

Thanks again for this suggestion, Rick. Unfortunately I'm drawing a blank here in Europe to find foam filters by roll or at least larger sheets. Are there any other brand names perhaps?

Rick A said:
https://www.amazon.com/Frost-King-C...l+foam+filter&qid=1560338312&s=gateway&sr=8-3

Rick A · Jun 13, 2019

You'll have to utilize whatever resources are available where you live. I only showed you what I have available for low money where I live.

philipus · Jun 13, 2019

Haha right, thanks Rick.

Rick A said:
You'll have to utilize whatever resources are available where you live. I only showed you what I have available for low money where I live.

mgb74 · Jun 13, 2019

You can buy filters specifically for computer fans. Not a supplier in Europe, but you should be able to find locally: https://www.microcenter.com/product/391504/120mm-fan-filter

philipus · Jun 14, 2019

Thank you for this suggestion.

mgb74 said:
You can buy filters specifically for computer fans. Not a supplier in Europe, but you should be able to find locally: https://www.microcenter.com/product/391504/120mm-fan-filter

mpirie · Jun 14, 2019

Have a look at: https://www.amazon.co.uk/s?k=cooker+filter&ref=nb_sb_noss_1

Mike

philipus · Jun 14, 2019

Thank you very much Mike, very helpful indeed.
br
Philip

mpirie said:
Have a look at: https://www.amazon.co.uk/s?k=cooker+filter&ref=nb_sb_noss_1

Mike

RauschenOderKorn · Jun 14, 2019

The following filter has an excellent rating and lets a lot of air pass though:

https://www.amazon.de/Swirl-Lüftung...YBZKAG8P393&psc=1&refRID=4WEYV2WNHYBZKAG8P393

philipus · Jun 14, 2019

Thank you, that looks very interesting too. Would it really let air through if used with a weak computer-type fan?

RauschenOderKorn said:
The following filter has an excellent rating and lets a lot of air pass though:

https://www.amazon.de/Swirl-Lüftung...YBZKAG8P393&psc=1&refRID=4WEYV2WNHYBZKAG8P393

John51 · Jun 14, 2019

A design I saw in the 70s used pantyhose as a filter. No fan though.

philipus · Jun 15, 2019

Haha well I might try that too, thank you John.

John51 said:
A design I saw in the 70s used pantyhose as a filter. No fan though.

M Carter · Jun 15, 2019

I've seen drying cabinets that didn't rely on a fan at all, but had something like a 60 watt light bulb under a tin plate at the bottom - the bulb warmed the air and convection cause the air to flow up and out the top. So a much more gentle approach to moving the air, which also added a few degrees of heat to speed drying. Always liked that idea.

M Carter · Jun 15, 2019

philipus said:
Hello everybody

I just wanted to share the prototype of a film dryer I've built. It's straight forward, easy and inexpensive to build. The one thing I would like to add is a thin air filter which doesn't block the airflow too much because I have chosen a pretty weak fan (deliberately). Any ideas on that?

My biggest comment is drying the film on reels means it's going to have the curl just baked in and may be hard to flatten the film - the film at the center of the reel seems like it would have a very extreme and tight curl after drying. I've seen some cool DIY dryers that use those plastic hanging wardrobe storage bags and allow you to hang rolls of film - that does take more space, but they can be folded flat when stored.

RauschenOderKorn · Jun 18, 2019

philipus said:
Thank you, that looks very interesting too. Would it really let air through if used with a weak computer-type fan?

The fan you are going for is actually quite weak, I did not see that in the first place. The filter is used in home ventilation systems which do not allow for much pressure loss. I guess it should work, but you can only be sure if you try.

DIY film dryer

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